Temperature Depression Research Articles

Gibbsian Surface Thermodynamics.

Gibbsian composite-system thermodynamics is the framework governing the equilibrium of composite systems, including systems that at equilibrium have more than one value of pressure because of the action of surface tension, semipermeable membranes, or fields, and thus cannot be treated as simple systems. J. W. Gibbs's paper that lays out composite-system thermodynamics, "On the Equilibrium of Heterogeneous Substances", communicated in two parts in 1876 and 1878, is widely regarded as one of the most important pieces of scientific literature of its century. Many scientists adopted and stressed the importance of Gibbsian thermodynamics. In 1960, H. B. Callen wrote a textbook that made Gibbsian composite-system thermodynamics more accessible to thermodynamicists. However, Callen's book left out Gibbs's work on curved fluid interfaces and did not treat the complicated nonideal systems of interest to today's thermodynamicists. In this Feature Article, I have attempted to convey in a comprehensive manner the framework of Gibbsian composite-system thermodynamics including in detail the treatment of systems with interface effects and with nonideal, multicomponent phases. This work lays out the relationships between important equilibrium equations including the following: the Gibbs-Duhem equation, the Gibbs adsorption equation, the Young-Laplace equation, the Young equation, the Cassie-Baxter equation, the Wenzel equation, the Kelvin equation, the Gibbs-Thompson equation, and the Ostwald-Freundlich equation, including nonideal and multicomponent forms. Equations of state that are often useful for Gibbsian composite-system thermodynamics are reviewed including adsorption isotherms and our own work on two semiempirical equations of state: the Elliott et al. form of the osmotic virial equation and the Shardt-Elliott-Connors-Wright equation for the temperature and composition dependence of surface tension. I summarize the work of our group developing Gibbisan composite-system thermodynamics including new equations for such things as the curvature-induced depression of the eutectic temperature or the removal of azeotropes by nanoscale fluid interface curvature. Gibbsian composite-system thermodynamics has broad applications in biotechnology, nanostructured materials, surface textures and coatings, microfluidics, nanoscience, atmospheric and environmental physics, among others.

Intraspecific diversity as a reservoir for heat-stress tolerance in sweet potato

Stable and sufficient food supplies are increasingly threatened by climatic variability, in particular extreme heat events. Intraspecific crop diversity may be an important biological resource to both understand and maintain crop resilience to extreme conditions. Here using data from a mass field experiment screening for heat tolerance in sweet potato (Ipomoea batatas), we identify 132 heat-tolerant cultivars and breeding lines (6.7%) out of 1,973 investigated. Sweet potato is the world's fifth most important food crop, and mean conditions experienced by sweet potato by 2070 are predicted to be 1 to 6 °C warmer, negatively impacting most genotypes. We identify canopy temperature depression, chlorophyll content and storage root-flesh colour as predictors of heat tolerance and, therefore, as potential traits for breeding consideration. These results highlight the role of intraspecific biodiversity for the productivity and resilience of food and agricultural systems in the face of climate change.

Characterizing moisture uptake and plasticization effects of water on amorphous amylose starch models using molecular dynamics methods

Dynamics and thermophysical properties of amorphous starch were explored using molecular dynamics (MD) simulations. Using the OPLS3e force field, simulations of short amylose chains in water were performed to determine force field accuracy. Using well-tempered metadynamics, a free energy map of the two glycosidic angles of an amylose molecule was constructed and compared with other modern force fields. Good agreement of torsional sampling for both solvated and amorphous amylose starch models was observed. Using combined grand canonical Monte Carlo (GCMC)/MD simulations, a moisture sorption isotherm curve is predicted along with temperature dependence. Concentration-dependent activation energies for water transport agree quantitatively with previous experiments. Finally, the plasticization effect of moisture content on amorphous starch was investigated. Predicted glass transition temperature (Tg) depression as a function of moisture content is in line with experimental trends. Further, our calculations provide a value for the dry Tg for amorphous starch, a value which no experimental value is available.

Assessment of Morpho-Physiological, Yield and Yield Attributing Traits Related to Post Anthesis Drought in Wheat Genotypes Under Rainfed Condition in Rampur, Chitwan

A set of twenty wheat (Triticum aestivum L.) genotypes was evaluated to assess morpho-physiological, yield and yield attributing traits related to post-anthesis drought in wheat genotypes under rainfed condition in a Randomized completely block design with three replications at research farm of Faculty of Agriculture, Rampur, Chitwan, during winter season of 2016/2017. The result revealed highly significant genotypic effects for number of tillers per m2 area, plant height, spike length, number of grains per spike, weight of grains per spike, 1000 kernels weight, days to booting, days to heading, days to anthesis, days to flag leaf senescence, days to maturity, SPAD meter reading, peduncle length, grain filling duration and reproductive growth period. Significant genotypic effects were found for grain yield, biological yield and harvest index and an array of variation was found among the genotypes for each trait. But non-significant genotypic effect was found for canopy temperature depression. WK2373 gave highest grain yield kg/ha (3035 kg/ha) and biomass yield kg/ha (8080 kg/ha).
 This study presented WK2373, WK2379, WK2380, WK2386, WK2388, WK2383, WK 2378 and WK1481 the best genotypes governing different valuable traits. These potential genotypes for valuable traits found in different clusters. Crossing genotypes belonging to different clusters could maximize the opportunities for transgressive segregation as there is a higher probability that unrelated genotypes would contribute unique desirable alleles at different loci. Therefore, this study can help breeders to increase genetic diversity by selecting materials of divergent parentage for crosses, thereby reducing vulnerability to diseases and climate changes. 
 Int. J. Appl. Sci. Biotechnol. Vol 8(3): 323-335

Impact of drought stress and stress modifiers on water use efficiency, membrane lipidation indices, and water relationship indices of pot marigold (Calendula officinalis L.)

This study was conducted as a factorial layout based on completely randomized design in three replications in the 2018. The experimental factors included irrigation intervals with 4 levels (3, 6, 9, and 12 days) and drought stress modifiers at four levels (control (non-spraying), spraying with salicylic acid (2 mM), Glycine betaine (5 mM), and zinc sulfate (5 g L−1). The results indicated that the effect of different levels of drought stress and stress modifiers on yield, water use efficiency, membrane lipidation indices, and water relationship indices were significant. The highest water use efficiency based on dry yield (WUEDY) (2.33 kg m−3) and water use efficiency based on essential oil yield (WUEEOY) (0.22 kg m−3) were obtained from irrigation intervals of three days. With increasing irrigation interval from three days to 12 days, dry yield, leaf water content, WUEEOY, cellular membrane stability (CMS), membrane stability index (MSI), total chlorophyll, chlorophyll index, canopy temperature depression (CTD), and relative water content decreased. However, injury index (I), water saturation deficit (WSD), osmotic potential (OP), electrolyte leakage (EL), essential oil percentage, and leaf temperature increased significantly. It seems that at all levels of irrigation, spraying with glycine betaine compared to other modifiers was more effective in increasing WUEDY, WUEEOY, CMS, MSI, total chlorophyll and relative water content, and decrease in I and WSD and EL. Based on the findings, it can be stated that with increasing the irrigation intervals, quantitative and qualitative yields of the pot marigold plant are reduced. The application of drought stress modifiers can reduce the effects of drought stress on this plant, thereby raising WUEDY and WUEEOY.

Dynamic behavior of reversible oxygen migration in irradiated-annealed high temperature superconducting wires

We use atomically resolved scanning transmission electron microscopy and electron energy loss spectroscopy to determine the atomic-scale structural, chemical and electronic properties of artificial engineered defects in irradiated-annealed high temperature superconducting wires based on epitaxial Y(Dy)BCO film. We directly probe the oxygen vacancy defects in both plane and chain sites after irradiation with 18-meV Au ions. The plane site vacancies are reoccupied during post-annealing treatment. Our results demonstrate the dynamic reversible behavior of oxygen point defects, which explains the depression and recovery of self-field critical current and critical temperature in irradiation-annealing process. These findings reveal the strong effect of oxygen vacancies in different sites on the superconductivity properties of irradiated Y(Dy)BCO film, and provide important insights into defects engineering of 2G HTS coil wires.

Study of the critical gas saturation during methane hydrate dissociation at the single-pore scale: Analytical solutions for large pores

Offshore/onshore deposits of methane hydrates could represent a large potential future source of energy, provided the difficulties associated with their safe, environmental-friendly and economically-viable production can be resolved adequately. Examining hydrate dissociation at different length scales (e.g., molecular, single pore, pore network, core and field) is part of the goal to initially identify, and subsequently address such difficulties. The current study introduces a mathematical-modeling approach and is focused on the evolution of methane gas that occurs within a single pore and is the result of the dissociation of methane hydrate that was originally deposited within the pore. We examine the critical gas saturation, which is defined as the fraction of gas volume inside a single pore when a spherical gas bubble reaches the pore walls for the first time. Further, we obtain critical values for pore sizes above which the production of methane gas is possible. The results shown here correspond to the case of large pores where the depression of the dissociation temperature (due to the presence of small-sized pores) is ignored.

Raindrop Signature from Microwave Radiometer Over Deserts

AbstractRainfall estimates from spaceborne microwave radiometers form the foundation of global precipitation data sets. Since the beginning of the satellite microwave rainfall estimation era in the 1980s, the primary signature leveraged over land for these estimates has been the brightness temperature (TB) depression due to ice particle scattering. Contrary to this practice, time series analyses based on observations from two spaceborne radars and two spaceborne radiometers reveal a TB increase at H19 due to raindrop emission as the primary cloud particle signature over desert terrain. Low surface emissivity supports the use of liquid raindrop emission as the primary signature over desert surfaces. In these regions, the surface rain rate better correlates with the liquid raindrop emission signal than with the scattering induced by ice further aloft, suggesting a new potential for improving rainfall estimation over deserts by exploiting the liquid raindrop emission signature.

Assessment of magmatic fertility using pXRF on altered rocks from the Ordovician Macquarie Arc, New South Wales

This research presents a new method for assessing magmatic fertility using the portable X-ray fluorescence spectrometer (pXRF) in altered rocks from porphyry terranes. A study of Northparkes and global Cu--Au porphyries highlighted low Zr and Y trends associated with mineralising intrusions. Zircon saturation occurs at low Zr concentrations owing to low-temperature crystallisation depressed by high dissolved H2O in the melt. Yttrium depletion indicates hydrous magmatic conditions that cause hornblende to crystallise early. Previously geochemical differentiation of hydrous, potentially ore-forming (fertile) porphyries has relied on ratios of Sr/Y and Sr/MnO from geochemical and/or pXRF analysis of least altered rocks. Strontium is highly mobile and limits its use in altered terranes. Finding samples in porphyry terranes where Sr can be demonstrated to be retained is difficult given the ubiquity of alteration associated with porphyry emplacement. This precludes the widespread use of pXRF, as quantitative assessment of alteration is beyond the capabilities of pXRF technology. Using immobile elements overcomes issues with alteration and provides more reliable indicators of magmatic fertility. Using a systematic pXRF workflow, plots of Zr vs Y and Zr*Y vs Al2O3/TiO2 were successful in identifying 100% of the mineralising intrusions in the Northparkes intrusive complex and provide an indication of magmatic fertility and a proxy for melt hydration state. The ratios of Zr/Nb vs Y/Nb are insensitive to alteration including weathering and are indicative of evolution and dissolved H2O content of magmatic sources. Moving from bivariate plots to ratio plots shifts the data into a real-number space and provides a linear function to assess against magmatic fertility. Application of the fertility indicators to a regional dataset from New South Wales highlights areas of known porphyry mineralisation indicating that the method has the potential to be a useful indicator of fertility beyond the scope of the pilot study. KEY POINTS The fertility of porphyry intrusions is directly related to their dissolved H2O content and oxidation state. High dissolved H2O content in magmas causes early crystallisation of hornblende, and temperature depression. As a result Zr saturation occurs at low Zr concentrations that results in depletion of Y and the MREE in hydrous rocks compared with normal arc rocks. Magmatic fertility can be rapidly and cheaply assessed in the field using Zr and Y concentrations from pXRF analyses. The use of immobile elements facilitates magmatic fertility assessment in altered rock, which was previously impossible owing to the use of mobile elements Sr and MnO.

Investigation of the Melting Point Depression of Copper Nanoparticles

In this paper copper nanoparticles (Cu NPs) have been produced by solvothermal method. One of the objectives of the present research was to create Cu NPs using aqueous medium technology. The analysis of the produced particles was performed by X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM). In the course of the experiments, copper core and organic shell nanoparticles were created successfully. It has been found that the average diameter of the created Cu NPs was 50 nm. The thermal behaviour of these particles was investigated by Differential Scanning Calorimetry (DSC). The melting temperature depression of the one-pot synthesized Cu NPs was 633 °C.

Temperature control of shoot growth and floral initiation in apple (Malus\u2009\xd7\u2009domestica Borkh.)

BackgroundThe environmental control of flowering in apple (Malus × domestica Borkh.) has remained an enigma for generations.MethodsWe studied growth and flowering effects of temperature under daylight phytotron conditions in 3-year old ‘Summerred’ and ‘Discovery’ apple trees. Flowering was assessed by dissection of buds on spurs and extension shoots at termination of treatments and flowering performance in the subsequent spring.ResultsExposure to constant temperatures ranging from 12 to 27 °C for 12 weeks yielded a hyperbolic response curve with optimum at 18–21 °C and little or no flowering at 12 and 27 °C. A drop from high to low temperature after 6 weeks caused growth cessation and initiation of flowering, whereas the reverse shift had the opposite effect. Shoot growth and leaf accumulation increased with increasing temperature, but under flower-inducing conditions, both levelled off and ceased towards the end of the treatment period.ConclusionsThe results are discussed in relation to the extensive physiological and genetic literature on the subject. We interpret the results as two separate effects of temperature on flowering in apple. At 12 °C flowering seems to be limited by low temperature depression of growth and leaf production, while at 27 °C, flowering is blocked by inhibition of the floral initiation itself. Intermediate temperatures of 18–21 °C, on the other hand, seem to satisfy the requirements for both processes. These opposite effects of temperature have apparently confounded the understanding of the environmental control of flowering in apple.

Influence of water of crystallization on the ternary phase behavior of a drug and deep eutectic solvent

Deep eutectic solvents (DESs) are mixtures of two solid components that interact via hydrogen bonds causing a large melting temperature depression. DESs are promising drug carriers and solvents for drugs with poor aqueous solubility. The presence of water within DESs is reported to change physicochemical properties, which could influence molecular interactions with drugs. It is therefore essential to study the influence of water of crystallization within one of the DES components on the drug loading capacity. In this study the influence of water of crystallization on the properties of two DESs containing xylitol and betaine anhydrate or monohydrate was investigated. Furthermore, the binary and ternary phase diagrams as well as the interplay between acetylsalicylic acid and the DES components were characterized to identify the maximum drug loading and elucidate the solvation mechanism. The presence of water of crystallization did not change the phase behavior of the binary DES, which had a eutectic melting temperature of 35–36 °C. Betaine anhydrate and acetylsalicylic acid formed a co-crystal after ball milling for 5 min with a melting temperature of 78 °C. Betaine monohydrate and acetylsalicylic acid formed a eutectic mixture with a melting temperature of 35 °C. Due to different interactions between the two crystal forms of betaine, the ternary phase behavior was significantly influenced by water of crystallization. The highest drug loading for the betaine anhydrate containing DES was 10 n/n% and was found at the eutectic composition of the DES. For the betaine monohydrate containing DES, the highest drug loading was 39 n/n% at a non-eutectic composition of the DES. These results demonstrated the importance of investigating the ternary phase behavior and influence of water of crystallization.

Speleothem and glacier records of latest Pleistocene–early Holocene climate change in the western North American interior

ABSTRACTRapid and high‐magnitude North Atlantic climate oscillations following the Last Glacial Maximum have been correlated to climate change events in western North America. However, the strength of teleconnections between the North Atlantic and the interior of western North America remains poorly understood. We present a U‐series calibrated speleothem record from Timpanogos Cave National Monument, located at 2040 m asl in the Wasatch Mountains of Utah, spanning 13.5–10.6 ka. Additionally, we carried out a climate reconstruction for a coeval glacier advance in the Wind River Range of Wyoming. Our results indicate that between 13.5 and 12.8 ka, the Wasatch was probably first cool and dry and then warmed. After 12.8 ka, our record suggests cool and/or wetter conditions followed by reduced moisture until 11.8 ka, followed by an early Holocene wet period. The Timpanogos record exhibits few similarities with those from the North Atlantic. Climate reconstructions of the Titcomb Basin glacier suggest modest temperature depressions relative to modern (<−3 °C) were necessary to sustain the glacier with a moderate increase in precipitation (>150%). The high‐altitude speleothem record presented here provides a valuable basis for understanding latest Pleistocene–early Holocene glacial episodes in western North America.

Use of infrared thermography imaging for assessing heat tolerance in high and low iron pearl millet lines

In the arid regions of Asia and Africa, pearl millet serves as a staple source of dietary energy and mineral micronutrients for millions of people. These regions are more vulnerable to increased temperature. The availability of rapid and efficient screening tools based on the relevant non-destructive quantifiable traits would facilitate pearl millet improvement for heat tolerance. The objective of this study was to evaluate pearl millet lines with contrast micronutrients for heat tolerance using infrared thermal imaging, a rapid proxy-canopy (panicle and flag leaf) temperature measurement. Results showed the highly significant genotypic differences between high-Fe and low-Fe genotypes for grain Fe and Zn densities and agronomic traits. Both high-Fe and low-Fe group genotypes differed significantly for panicle temperature depression (PTD) during high- vapor deficit (VPD) at stigma stage (3.0 to 6.73°C). PTD values were positive across all genotypes during stigma stage and were very low or negative during the low-VPD. Cooler canopy temperature (high-PTD) was observed during stigma stage rather than seed-set stage at higher-VPD in both high-Fe and low-Fe genotypes. The cooler temperature achieved by panicle might be helpful in maintaining stigma receptivity for longer periods in the female parents, whereas in male parents it might be helpful in maintaining pollen viability for longer periods. Flag leaf temperature (FTD) was cooler than PTD at both high-VPD and low-VPD as well in both stigma (less by 2.1°C) and grain-filling stage (less by 2.7°C), again signifying that the reproductive parts are more prone to heat stress as compared to vegetative parts. Since, thermal imaging discriminates the heat stress and non-stress canopies, this can serve as a proxy canopy temperature tool for heat stress tolerance screening in pearl millet.

Extension and Limits of Cryoscopy for Nanoconfined Solutions.

This work investigates the phase behavior of aqueous solutions of glycerol confined in MCM-41 and SBA-15 nanoporous matrixes by calorimetry. Limitations due to overfilling and eutectic freezing are prevented by the absence of an external liquid reservoir and by the glass-forming property of glycerol. Consequently, the stability of nanoconfined ice in equilibrium with aqueous solutions is studied over a wide range of compositions. In confinement, a large temperature depression of the liquidus line is observed. A thermodynamic model accounting simultaneously for the cryoscopic and the Gibbs-Thomson effects gives a consistent view of the phase diagram for large pores (Rp = 4.15 nm). For smaller pores (Rp = 1.8 nm), it reveals that the water activity strongly deviates from the bulk solution with the same composition, indicating the possible role of concentration heterogeneities in determining the onset of ice freezing in strongly nanoconfined solutions.

Phase behaviors of n-octacosane in nanopores: Role of pore size and morphology

The nanoconfinement effect on the phase behaviors of octacosane (n-C28H58, C28) was studied using differential scanning calorimetry (DSC) and X-ray diffraction (XRD). In the nanopores of controlled pore glasses (CPGs), silica gels (SGs), SBA-15, and KIT-6, C28 showed depressed phase transition temperatures. The depression of phase transition temperatures, degree of supercooling and enthalpies of phase transitions for C28 confined in the CPGs, SGs and SBA-15 exhibited a linear dependence on reverse pore diameter. The phase transition temperatures also varied with the changing pore geometry, and the depression of melting points of C28 in SBA-15 is about 2 times larger than that in the CPGs and SGs. The interfacial interactions of the pore walls to alkane seem to have a negligible influence on the phase behaviors. The phase transition sequences of the pore-confined C28 changed largely with the appearance of new RI and RII rotator phases.

Canopy temperature depression and normalized difference vegetation index as indicators of drought resistance and nitrogen recommendation in hybrid maize genotypes

Canopy temperature depression and normalized difference vegetation index as indicators of drought resistance and nitrogen recommendation in hybrid maize genotypes

Canopy temperature depression and normalized difference vegetation index as indicators of drought resistance and nitrogen recommendation in hybrid maize genotypes

Canopy temperature depression and normalized difference vegetation index as indicators of drought resistance and nitrogen recommendation in hybrid maize genotypes

Population structure, marker-trait association and identification of candidate genes for terminal heat stress relevant traits in bread wheat (Triticum aestivum L. em Thell)

AbstractGenetic improvement along with widened crop base necessitates for the detailed understanding of the genetic diversity and population structure in wheat. The present investigation reports the discovery of a total of 182 alleles by assaying 52 simple sequence repeats (SSRs) on 40 genotypes of bread wheat. Unweighted neighbour-joining method grouped these genotypes into two main clusters. Highly heat tolerant and intermediate tolerant cultivars were grouped in the same cluster, whereas remaining genotypes, particularly sensitive ones, were assigned different cluster. Similarly, the entire population was structured into two sub-populations (K = 2), closely corresponding with the other distance-based clustering patterns. The marker-trait association was discovered for four important physiological parameters, viz. canopy temperature depression, membrane thermostability index (MSI), normalized difference vegetation index and heat susceptibility index, indicating for heat stress (HS) tolerance in wheat. Both general and mixed linear models of association studies during 2017 and 2018, revealed the association of SSR markers, wmc222 (17.60%, PV) and gwm34 (20.70%, PV) with the mean phenotypic value of MSI. Likewise, SSR markers barc183, gwm75, gwm11 and cfd7 revealed a unique relationship with four selected physiological traits. Candidate genes discovered using in silico tools had nine SSR markers within the genic regions reported to play a role in heat and drought stress responses in plants. The information generated about these genic regions may be explored further in expression studies in-vivo to impart HS tolerance in bread wheat.

Clumped isotope constraints on changes in latest Pleistocene hydroclimate in the northwestern Great Basin: Lake Surprise, California

AbstractDuring the Last Glacial Maximum (LGM) and subsequent deglaciation, the Great Basin in the southwestern United States was covered by numerous extensive closed-basin lakes, in stark contrast with the predominately arid climate observed today. This transition from lakes in the Late Pleistocene to modern aridity implies large changes in the regional water balance. Whether these changes were driven by increased precipitation rates due to changes in atmospheric dynamics, decreased evaporation rates resulting from temperature depression and summer insolation changes, or some combination of the two remains uncertain. The factors contributing to these large-scale changes in hydroclimate are critical to resolve, given that this region is poised to undergo future anthropogenic-forced climate changes with large uncertainties in model simulations for the 21st century. Furthermore, there are ambiguous constraints on the magnitude and even the sign of changes in key hydroclimate variables between the Last Glacial Maximum and the present day in both proxy reconstructions and climate model analyses of the region. Here we report thermodynamically derived estimates of changes in temperature, precipitation, and evaporation rates, as well as the isotopic composition of lake water, using clumped isotope data from an ancient lake in the northwestern Great Basin, Lake Surprise (California). Compared to modern climate, mean annual air temperature at Lake Surprise was 4.7 °C lower during the Last Glacial Maximum, with decreased evaporation rates and similar precipitation rates to modern. During the mid-deglacial period, the growth of Lake Surprise implied that the lake hydrologic budget briefly departed from steady state. Our reconstructions indicate that this growth took place rapidly, while the subsequent lake regression took place over several thousand years. Using models for precipitation and evaporation constrained from clumped isotope results, we determine that the disappearance of Lake Surprise coincided with a moderate increase in lake temperature, along with increasing evaporation rates outpacing increasing precipitation rates. Concomitant analysis of proxy data and climate model simulations for the Last Glacial Maximum are used to provide a robust means to understand past climate change, and by extension, predict how current hydroclimates may respond to expected future climate forcings. We suggest that an expansion of this analysis to more basins across a larger spatial scale could provide valuable insight into proposed climate forcings, and aid in climate model process depiction. Ultimately, our analysis highlights the importance of temperature-driven evaporation as a mechanism for lake growth and retreat in this region.